For rotating machines operated at high speeds, a tilting pad journal bearing as shown in non-patent document 1 is often employed. This tilting pad journal bearing generally includes a plurality of pads disposed on the outer circumferential side of a rotating shaft and subjected to radial load on the rotating shaft, a plurality of pivots each supporting a corresponding one of the pads in such a manner that the pads are tiltable, and a casing housing the pads and the pivots. When the rotating shaft is rotated, lubricating oil is introduced between the rotating shaft and the pads to form wedged oil films therebetween. In this case, since the pad can be tilted, the rotating shaft is eccentric and a load is applied to the rotating shaft in a direction corresponding to the eccentricity, which attains good vibration stability. Thus, the tilting pad journal bearings are widely employed for high-speed rotating machines such as steam turbines, gas turbines and centrifugal compressors.
In recent years, rotating machines such as steam turbines and the like have been enlarged in order to increase efficiency. A tilting pad journal bearing supporting a rotating shaft of the rotating machine needs to catch up with high circumferential velocity and high surface pressure attributable to the enlargement. Specifically, the inner circumferential surface of a pad, which is a sliding surface with the rotating shaft, generates friction heat and seizure is more likely to occur with higher circumferential velocity and higher surface pressure. It is, therefore, necessary to provide some contrivance to reduce the temperature of the inner circumferential surface of the pad.
In view of the above, the conventional technology described in e.g. patent document 1 has a lubricating oil supply passage formed inside each of pads so as to cool the pad. The lubricating oil supply passage extends from one end side to the other end side of the pad in the circumferential direction. A flexible pipe is coupled to the inlet of the lubricating oil supply passage formed on one end side (in other words, on the downstream side in the rotational direction of the rotating shaft), in the circumferential direction, of the pad. A blowoff block is integrally secured to the other end side (in other words, on the upstream side in the rotational direction of the rotating shaft), in the circumferential direction, of the pad. An oil-lead passage of the blowoff block is connected to the outlet of the lubricating oil supply passage formed on the other end side, in the circumferential direction, of the pad. In this way, lubricating oil is led to the lubricating oil supply passage of the pad via the flexible pipe, is caused to flow in the lubricating oil supply passage of the pad in the direction opposite to the rotational direction of the rotating shaft and is led to the oil-leading passage of the blowoff block. The lubricating oil is then sprayed toward the outer circumferential surface of the rotating shaft via nozzles of the blowoff block. Thus, the pad can effectively be cooled and lubricated at a small oiling quantity without a stirring loss.